Don't know if you've seen this page already, it's from a swedish rally enthusiast:
http://www.ampe.info/rallybore2/
There you can see Lars Ingvar, plus one other driver (Karl Gunnar Blomqvist) in another mini, jumping over a small bump on the Bore Rally in 1966. Sadly neither are the photo you were looking for, but might be fun to see nontheless :)
Here are some more picture from the Östgöta Rally in 1967:
http://old.lms.se/ra...allyt_1967.html
Once again some jumping minis, but sadly not the photo you're after...
Did find this one which is a bit more similar though:
That's from a thread on the mk1 forum, the topic of which mentions something about the BMC Sweden works cars... Sadly I'm not a member there so I couldn't investigate further. Maybe there's something there?
Regards,
Anton.